Radios, tape players, sound systems or other equipment having an audio output require alignment during manufacture and may need sound quality testing. For these purposes audio analyzers are known which perform a variety of tests and are very expensive; such equipment includes dedicated boards including microprocessors for digital signal processing and control panels. When using such analyzers with a test controller which supervises analyzer operation as applied to a large number or variety of products, additional costs are invoked for interface circuits for communication with the test controller as well as for a computer which comprises the controller.
The dedicated analyzer, moreover, includes a fixed set of standard filters which are useful for audio analysis but has no provision for the addition of specialized filters which may be needed for testing certain products. In addition, the measurement technique itself is fixed and new techniques cannot be used. Even the simple improvement of sampling for a longer signal interval is not possible due to limited memory in the analyzer. In short, the dedicated analyzer is not flexible.
It has been found that by using relatively inexpensive general purpose microprocessor apparatus for the signal processing, equivalent analysis can be performed by equipment at a fraction of the cost of the known analyzers.